This invention relates to gate valves, and, more specifically, to locking gate valves. Although the invention is widely applicable for its purpose, it has special utility in poultry watering systems.
In the environment of gate valves, it is known to provide a body wherein an opening forms a flow passage. A slideable valve member is typically enclosed within the body and connected by a stem or rod to external means for manipulating the valve into open and closed positions relative to the flow passage. It is also known to provide for sealing means about the valve to prevent leakage when the valve is in a closed position. However, many prior gate valves do not have locking means to prevent inadvertent opening of the flow passage. Prior gate valves that have incorporated locking means for keeping the valve shut typically require significant amounts of time and effort by multi-step techniques for opening or closing and locking the valve in a closed position.
U.S. Pat. No. 3,443,788 shows a gate valve which prevents inadvertent flow through the use of locking pins. However, these locking pins must be turned into the locking position in a separate motion after the gate valve has been closed. This arrangement requires more time and is more inconvenient than a one-step or single action locking method.
U.S. Pat. No. 3,316,929 locks down the gate valve. However, the valve must be pressed closed and then the handle must be rotated to engage the handle on a ledge of the body. Further, because of the force of the springs, the operator may not know without a visual check if the handle has been properly locked in the closed position.
In poultry watering systems it is especially important that the gate valve be securely locked when closed. Poultry have a tendency to roost on portions of the watering equipment, including the external portion of the valve stem. If the valve is not securely locked, the valve may be accidentally opened by the poultry and the resulting excessive water flow could lead to flooding of the poultry cage area. At the same time, a large number of these valves need to be opened and closed manually at several times during a single day in typical poultry operations. Thus, it is desirable that the opening and closing mechanisms and techniques also be simple, relatively fast, and inexpensive.
It is therefore an object of the present invention to provide a gate valve which prevents inadvertent opening of the flow passage.
It is a further object of the present invention to provide a gate valve which can be closed and locked shut with a single, short axial motion.
It is a further object of the present invention to provide a gate valve which may be securely locked closed to prevent inadvertent opening by poultry and readily opened by an operator.
It is a further object of the present invention to assure the operator that the gate valve has been locked in the closed position.
These and other objects are achieved in accordance with a preferred embodiment of the present invention by providing a gate valve having a body with integral catches thereon. Resilient latches are integrally formed on the valve stem, which is rotatably attached to the valve member, such that they can be bent over the catches on the body and snap lock the gate valve in the closed position with a single axial motion. To release the lock, the stem and latches are rotated off the catches, and the valve can be freely moved from the closed to opened positions. The gate valve body is formed by the ultrasonic welding of two identical half members made from the same mold. The body has seals attached to the inside of each half member which surround the flow passage on either side of the valve member. The stem is manipulated axially to move the gate valve into and out of the closed position.